import java.util.Scanner;
public class PaiLie {
    public static void main(String args[]) {
        Scanner reader = new Scanner(System.in);
        int m = reader.nextInt();
        System.out.println("m="+m);
        int n = reader.nextInt();
	System.out.println("n="+n);
        int a = 1;
        int b = 1;
        for (int i = 0; i <= (n - 1); i++) {
            a = a * (n - i);
        }
        if (n > m) {
            for (int t = 0; t <= (n - m - 1); t++) {
                b = b * (n - m - t);
            }
            int x = a / b;
            System.out.println("P(n,m)=" + x);
        } else {
            System.out.println("错误");
        }
    }
}
